Abstract: Objectives: The objective of this study was to assess the prevalence and molecular epidemiology of ESBLproducing
Escherichia coli causing healthcare-associated (HCA) and community-associated (CA) bacteraemia
of urinary origin (BUO) in Spain.
Methods: An observational cohort study was conducted at eight hospitals from different Spanish geographical
areas (2010?11). BUO episodes (n¼425) were classified as HCA (n¼215) and CA (n¼210), and one blood isolate
per episode was collected. Susceptibility testing was performed, ESBLs were screened by double-disc diffusion test
and ESBL and OXA-1 genes were characterized (PCR and sequencing). Population structure (phylogenetic groups,
XbaI-PFGE and MLST) and ST131 subtyping (PCR)were determined. Virulence genes were detected by PCR and virulence
score, profiles and extraintestinal pathogenic E. coli (ExPEC) status calculated.
Results: ESBL-producing E. coli prevalence was 9.2% (39/425). ESBL-producing E. coli episodes were significantly
associated with HCA-BUO episodes [14% (30/215) versus 4.3% (9/210); P¼0.001]. The highest non-susceptibility
proportions corresponded to ciprofloxacin (97.4%), amoxicillin/clavulanate (74.4%), co-trimoxazole (69.2%)
and tobramycin (61.5%). Of the 39 ESBL-producing E. coli isolates, 34 produced CTX-M enzymes (21 CTX-M-15,
11 CTX-M-14 and 2 CTX-M-1). Fifteen STs were identified, the B2-ST131 clone being the most prevalent (54%;
21/39). All ST131 isolates were ExPEC and had the highest virulence scores, but they showed less diversity in
virulence profiles than other STs. The H30Rx subclone accounted for most ST131 isolates (20/21), co-produced
CTX-M-15 (20/20) and OXA-1 (19/20) enzymes and was associated with HCA episodes (16/20).
Conclusions: The CTX-M-15-ST131-H30Rx subclone is a relevant MDR pathogen causing BUO, mainly HCA episodes.
The dominance of this subclone with comparatively less diversity of virulence profiles reflects the spread of a successful
and MDR ESBL ST131 lineage in Spain.